It is one of the most evocative titles in sport: the world heavyweight boxing champion.

Yet it is a title that has too often been fractured as a result of the rise of numerous different governing bodies in the years since the outstanding Muhammad Ali was stripped of the title in the late 1960s for refusing United States military service in the Vietnam War.

Joshua- Parker

But the current picture will become clearer when Britain’s Anthony Joshua, the International Boxing Federation and World Boxing Association champion, faces New Zealand’s Joseph Parker, the World Boxing Organisation title-holder, in a heavyweight unification bout on Saturday.

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Some 78,000 spectators are expected at Cardiff’s Principality Stadium, a testament to the enduring appeal or the heavyweight crown in general and the pulling power of Joshua in particular.

Joshua’s life story reads like the outline plot of a movie — a boy who fell in with the ‘wrong crowd’ but avoided prison because of his involvement in boxing and went on to win an Olympic gold medal in front of his home London crowd in 2012 before turning pro and building up an unbeaten 20-fight record in the paid ranks.

But Parker, two years younger at 26, also has a perfect professional record with 24 wins, 18 by way of knockout.

Saturday’s fight will be the first time two undisputed heavyweight champions have met for the title in Britain and should move the winner closer to a bout against Deontay Wilder, the American who holds the World Boxing Council’s version.

– ‘Hunted’ –Joshua may be the favourite in the eyes of many pundits but he said this week: “You still need to keep that challenger’s mindset. I’m still the challenger in my head.

“Sometimes I try and not be seen with the belts too much, I let other people do the enjoyment because I’ve got to do the challenger mindset.

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“I’m looking forward to the challenge of Parker but, just because now I’m the hunted, it’s not time to put my feet up and relax, I’m out there defending my throne on Saturday night.”

Joshua’s punching power — all 20 of his wins have been knockout victories — has revived interest in the heavyweight division and helped make him a box-office draw.

He has fought before at the Principality, defeating Carlos Takam there in October and Joshua believes this will give him an edge.

“I’m ready for the challenge. Parker is not,” wrote Joshua in his column for Thursday’s London Evening Standard.

“He won’t have encountered anything like the roof closed — a Dragon’s Den at the Principality Stadium.”

Joshua added: “He’ll find out very quickly on Saturday night that there is nowhere to hide with 78,000 fans wanting to see me knock him out.”

Parker, however, believes an edge in movement and ringcraft, will help him overcome the heavier Joshua’s reach advantage.

“I’m young, hungry, fit and strong,” he said. “I’ve got my speed back and I’ll show you on Saturday.”

The Principality is best known as the home of the Wales rugby union team, and when world champions New Zealand come to Cardiff, they usually leave with a victory — the last time they lost to Wales in the Welsh capital was back in 1953.

But the Principality was also the venue where the All Blacks suffered a shock quarter-final defeat by France at the 2007 World Cup.

“The All Blacks always do great here in Wales so I’m looking forward to keeping that record clean,” said Parker.

But one clean record will be lost this weekend as boxing moves one step close to the goal of an undisputed heavyweight champion of the world.